The Digital Preservation of Rani Ki Vav in India

Located in northeastern India, in the city of Patan in the state of Gujarat, is a traditional stepwell carved deep into the ground. The well is decorated with over 400 intricately carved niches. Rani Ki Vav, which translates as The Queens Stepwell, was built by Udaymati, Queen consort to Bhimdev I of the Solanki Dynasty, in 1050 CE. Although the well is nearly one thousand years old, much of the Hindu iconography is pristinely preserved. Over the centuries, the stepwell fell into disuse and was eventually flooded and filled with silt, protecting the monument from erosion. It was rediscovered in the 1960s, excavated in the 1980s, and today is on the Tentative List for UNESCO World Heritage nomination.

The spectacular artistic detail, and challenging physical nature of the stepwell, from its multi-terraced decent and multi-story colonnades, to its 27m depth, created the perfect opportunity to utilize 3D capture technologies to record the ancient structure. The significance of the Rani Ki Vav made it an ideal candidate for the next challenging international project of the Scottish Ten [link:]. The Scottish Ten is a collaborative effort between Historic Scotland (HS), the Glasgow School of Arts (GSA), and CyArk [link:] to digitally preserve the five World Heritage Sites of Scotland and five internationally significant heritage sites around the world. The Scottish Ten grew out of a response to a challenge laid out by CyArk founder Ben Kacyra to then Scottish Minister of Culture and External Affairs, Michael Russell. As part of CyArks efforts to digitally preserve the worlds cultural heritage, Mr. Russell committed the Scottish Government and its heritage arm, Historic Scotland, to the digital preservation of 10 heritage sites.

In late October 2011 at Rani Ki Vav, the Scottish and CyArk teams worked closely with the Archaeological Survey of India to ensure the full digital capture of the stepwell. This was accomplished using a time of flight laser scanner, a phase-based laser scanner, a structured light hand scanner, HD video, photogrammetry, HDR panoramic and HDR gigapan panoramic imaging, and high-resolution digital photography. Most scanning was performed by HS and GSA staff. However through daily hands-on training and sharing of their technical expertise, the Scottish team was able to empower the ASI to assist in some of the scanning during the second week of field work. CyArk, in addition to general support, once again played a key role in on-site data management and field capture organization. As the long term repository for the data, CyArk ensured the data collected was to the standards required for the CyArk archive and that the data was properly managed on site. This was similar to the role carried out for the first international Scottish Ten site at Mount Rushmore National Memorial, USA [link:].

Daily registration and back-up of data occurred to ensure the complex site was wholly mapped in 3D. This happed live, on-site in a make-shift command center of scaffolding and tarps, complete with power supply. Work diligently continued in the humidity, with occasional breaks to feed the local gray langur monkeys. Throughout each work day, hundreds of photographic images would be brought for data-dump as multiple 32GB compact flash cards were filled with images from the plethora of Nikon D3xs in use. The command center housed the working laptops, bundles of cables, and 3 LaCie Rugged Hard Drives totalling 2.5 TB of storage. One drive was considered the working drive while the two others served as back up. Complete daily data back-ups occurred each night while the team slept, and during the return trip from India, each drive left the country in the hands of a different team member to ensure all drives were not localized together in case of damage, theft, or loss.

In all, approximately 175 scans were captured with the two laser scanners. This laser scan data will be supplemented by the thousands of photographs taken and the Artec submillimeter data capture on several selected significant niche statues. The team did a tremendous job in capturing the required detail in spite of the machines regularly over-heating. (scanners, laptops, and hard drives alike) The final resulting registration will likely have in the range of 5 billion data points to represent the monument, which is 27m deep at its deepest end, 64m in length, and 20m in width. This level of coverage is required to capture the intricate figures of the niches of Rani Ki Vav, from their beaded necklaces, to their delicately curled toes. One test utilizing Autodesks Photofly was conducted on the niche of Varaha (a boar-headed incarnation of Vishnu); the 120 photographs taken of Varaha resulted in a superbly detailed 3.1 million triangle mesh.

The registration and management of so much information flooding in daily was, in itself, a monumental challenge. With overheating computers in the hot Indian climate, as well as irregular power supplies in the remote location, the task had daily hurdles to over-come. As the individual scan clouds came together, we saw the impressive coverage from single laser scansbeyond our own initial expectations. There was huge excitement as we saw the details of the Hindu icons materialize on screen. There is no doubt the final 3D data set for this project will be one of the finest in the CyArk archive, and a testament to the ingenuity of the Scottish Ten team.